Heat transfer member and method for manufacturing same

ABSTRACT

A heat transfer member for a heat exchanger, is press-formed of a metallic thin sheet material into a prescribed shape by means of molds of a press forming device so that the heat transfer member has on at least one portion thereof a heat transfer face having opposite surfaces, which are to be brought into contact with heat exchange fluids, respectively. The heat transfer face comprises at least one set of irregularity patterns arranged in a row. Each of the at least one set of irregularity pattern units comprises (i) a central pattern portion having a plurality of recesses or projections provided with a prescribed pitch, (ii) a pair of heat exchanging irregularity pattern portions provided on opposite sides of the central pattern portion so as to be symmetrical with respect to the central pattern portion and (iii) at least one boundary pattern portion provided on at least one of respective outer sides of the pair of heat exchanging irregularity pattern portions so as to be adjacent to the respective outer sides thereof. The boundary pattern portion has a prescribed width and a plurality of recesses or projections provided with a same pitch as the plurality of recesses or projections of the central pattern portion so as to be in parallel therewith.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates a heat transfer member for a heatexchanger, which is obtained by press-forming material to be worked, onthe one hand, and a method for manufacturing such a heat transfermember, on the other hand, and especially to the heat transfer member inwhich a plurality of press-formed portions having a prescribed shape arearranged, on the one hand, and the method for manufacturing same, bywhich the press-formed portions can be formed on the material to beworked in an appropriate arrangement.

[0003] 2. Description of the Related Art

[0004] If there is a wish that heat transfer coefficient is increased toenhance heat exchange effectiveness, utilizing a heat exchanger by whichheat exchange is made between a high temperature fluid and a lowtemperature fluid, a plate-type exchanger has conventionally been usedwidely. The plate-type exchanger has a structure in which a plurality ofheat transfer members having a plate-shape are placed parallelly oneupon another at prescribed intervals so as to form passages, which areseparated by means of the respective heat transfer member. A hightemperature fluid and a low temperature fluid flow alternately in theabove-mentioned passages to make heat exchange through the respectiveheat transfer members.

[0005] Such a heat transfer member, which has patterns of irregularity,is usually formed of a metallic thin sheet. The heat transfer member canbe manufactured by a press-forming method utilizing a press-formingdevice and put into practical use. A set of forming molds hasconventionally been used in order to form the heat transfer member. Morespecifically, a metallic thin sheet serving as material to be worked isplaced between the set of molds so that relative movement of the moldsform the heat transfer member having a prescribed shape such as a heattransfer face on the metallic sheet.

[0006] The conventional heat transfer member having the above-describedstructure causes a problem of making deformation of the heat transfermember thorough pressure of fluids to bring the adjacent heat transfermembers into contact with each other, when the distance between theadjacent heat transfer members is extremely small and there exists alarge pressure difference between a high pressure fluid and a lowpressure fluid, which flow along the opposite surfaces of the heattransfer member. Such a problem leads to improper change in distancebetween the adjacent heat transfer members and damage to the heattransfer face, thus causing possibility that effective heat exchange maynot be performed.

[0007] The heat transfer face of the heat transfer member has a patternof irregularity with various shapes in order to improve heat transfereffectiveness and condensation property. When the heat transfer face hasa non-uniform pattern, in which the pitch of the irregularity becomessmall on the one end of the heat transfer face and large on the otherend thereof, degree of drawing of material from a non-press formedportion into a press-formed portion in the press formation variesdepending upon a position of pattern of irregularity. A remarkableresidual distortion exists in the pressed portion and the non-pressedportion of the heat transfer member after completion of the pressformation, thus causing problems of warp of a part or entirety of theheat transfer member and deformation thereof.

SUMMARY OF THE INVENTION

[0008] An object of the present invention, which was made to solve theabove-mentioned problems, is therefore to provide a heat transfer memberin which prescribed press-formed portions are formed in addition to apattern of irregularity serving as the heat transfer face so as toprevent abnormal deformation and maintain a proper distance between theadjacent heat transfer members, thus making a reliable heat exchange, onthe one hand, and a method for manufacturing such a heat transfermember, on the other hand.

[0009] In order to attain the aforementioned object, a heat transfermember of the first aspect of the present invention for a heatexchanger, which is press-formed of a metallic thin sheet material intoa prescribed shape by means of molds of a press forming device so thatsaid heat transfer member has on at least one portion thereof a heattransfer face having opposite surfaces, which are to be brought intocontact with heat exchange fluids, respectively,

[0010] wherein:

[0011] said heat transfer face comprises at least one set ofirregularity patterns arranged in a row, each of said at least one setof irregularity pattern units comprising (i) a central pattern portionhaving a plurality of recesses or projections provided with a prescribedpitch, (ii) a pair of heat exchanging irregularity pattern portionsprovided on opposite sides of said central pattern portion so as to besymmetrical with respect to said central pattern portion and (iii) atleast one boundary pattern portion provided on at least one ofrespective outer sides of said pair of heat exchanging irregularitypattern portions so as to be adjacent to the respective outer sidesthereof, said at lest one boundary pattern portions having a prescribedwidth and a plurality of recesses or projections provided with a samepitch as said plurality of recesses or projections of said centralpattern portion so as to be in parallel therewith.

[0012] According to the first aspect of the present invention, there isformed a single set or a plurality of sets of press-formed portioncomprising the central pattern portion having the plurality of recessesor projections, the pair of heat exchanging irregularity patternportions provided on the opposite sides of the central pattern portionso as to be symmetrical with respect to the central pattern portion andthe at least one boundary pattern portion having the plurality ofrecesses or projections, which is provided on the at least one of therespective outer sides of the pair of heat exchanging irregularitypattern portions, so that the whole of the central pattern portion, theheat exchanging irregularity pattern portions and the boundary patternportion serves as the single heat transfer face. When the heat transfermember is placed on the other heat transfer member so that the innersurfaces of them face each other and the latter is positioned upsidedown, the projections of the central pattern portion and the projectionsof the boundary pattern portion of the one heat transfer member comeinto close contact with those of the other heat transfer member,respectively. It is therefore possible to maintain a constant distancebetween the heat transfer members, thus coping with a case where thereis a large difference in pressure between the heat transfer fluids.Accordingly, a uniform heat exchange property can be provided and areliable strength of the whole heat exchanger, which is composed of thecombined heat transfer members, can be obtained. Even when the heatexchanging irregularity pattern portion has a non-uniform pattern in thevertical direction of the heat transfer face, the boundary patternportions having the uniform pattern, are disposed outside the heatexchanging irregularity pattern portion, so as to reduce residualdistortion after completion of the press formation, preventing abnormaldeformation of the respective portions of the heat transfer member.

[0013] In order to attain the aforementioned object, a heat transfermember of the second aspect of the present invention for a heatexchanger, is press-formed of a metallic thin sheet material into aprescribed shape by means of molds of a press forming device so thatsaid heat transfer member has on at least one portion thereof a heattransfer face having opposite surfaces, which are to be brought intocontact with heat exchange fluids, respectively,

[0014] wherein:

[0015] said heat transfer face comprises at least one set ofirregularity patterns arranged in a row, each of said at least one setof irregularity pattern units comprising (i) a central pattern portionhaving a plurality of recesses or projections provided with a prescribedpitch, said central portion having two pairs of opposite sides, (ii) apair of heat exchanging irregularity pattern portions provided on one ofsaid two pairs of opposite sides of said central pattern portion so asto be symmetrical with respect to said central pattern portion, saidpair of heat exchanging irregularity pattern portions and said centralpattern forming a pair of opposite connection sides extending along another of said two pairs of opposite sides of said central patternportion, and (iii) at least one boundary pattern portion provided on atleast one of said pair of opposite connection sides, said at least oneboundary pattern portion having a prescribed width and a plurality ofrecesses or projections with a prescribed pitch so as to beperpendicular to said plurality of recesses or projections of saidcentral pattern portion.

[0016] According to the second aspect of the present invention, there isformed a single set of a plurality of sets of press-formed portioncomprising the central pattern portion having the plurality of recessesor projections, the pair of heat exchanging irregularity patternportions provided on the opposite sides of the central pattern portionso as to be symmetrical with respect to the central pattern portion andthe at least one boundary pattern portion having the plurality ofrecesses or projections, which is provided on the at least one of thepair of opposite connection sides. The at least one boundary patternportion has the prescribed width and the plurality of recesses orprojections with a prescribed pitch so as to be perpendicular to therecesses or projections of the central pattern portion. When the heattransfer member is placed on the other heat transfer member so that theinner surfaces of them face each other and the latter is positionedupside down, the projections of the central pattern portion and theprojections of the boundary pattern portion of the one heat transfermember come into close contact with those of the other heat transfermember, respectively. It is therefore possible to maintain a constantdistance between the heat transfer members, thus coping with a casewhere there is large difference between the heat transfer fluids.Accordingly, a uniform heat exchange property can be provided and areliable strength of the whole heat exchanger, which is composed of thecombined heat transfer members, can be obtained. Even when the centralpattern portion and the heat exchanging irregularity pattern portionhave a non-uniform pattern in the horizontal direction of the heattransfer face, the boundary pattern portions having the uniform pattern,are disposed on the adjacent portions, so as to reduce residualdistortion after completion of the press formation, preventing abnormaldeformation of the respective portions of the heat transfer member.

[0017] In the third aspect of the present invention, said boundarypattern portion may continue in a form of grooves or projections in adirection perpendicular a direction of said plurality of recesses orprojections thereof so as to form a plurality of rows of irregularities,providing a smooth wave-shaped cross section..

[0018] According to the third aspect of the present invention, theboundary pattern portion continues in a form of grooves or projectionsin the perpendicular direction to the plurality of recesses orprojections thereof so as to form a plurality of rows of irregularities,providing the smooth wave-shaped cross section.. When the heat transfermember is placed on the other heat transfer member so that the innersurfaces of them face each other and the latter is positioned upsidedown, the respective projections of the boundary pattern portions comeinto contact with each other. The number of contact points of theboundary pattern portions can be reduced, thus minimizing the contactareas of the boundary pattern portions so as to ensure a gapcommunicating with the boundary pattern portion. Accordingly, when theheat transfer member serves as a condenser, smooth flow of the heatexchange fluid in liquid phase can be ensured without causing buildup,thus enhancing the heat exchange effectiveness in the heat transferface. The recesses or projections of the smooth wave-shaped crosssection improve formability of the boundary pattern portions, thusavoiding defects of the products.

[0019] In the fourth aspect of the present invention, said centralpattern portion or said boundary pattern portion may continue in a formof grooves or projections in a direction of said plurality of recessesor projections thereof so as to form a plurality of rows ofirregularities, providing a smooth wave-shaped cross section.

[0020] According to the fourth aspect of the present invention, thecentral pattern portion or the boundary pattern portion continues in theform of grooves or projections in the direction of the plurality ofrecesses or projections thereof so as to form the plurality of rows ofirregularities, providing the smooth wave-shaped cross section. When theheat transfer member is placed on the other heat transfer member so thatthe inner surfaces of them face each other and the latter is positionedupside down, the respective projections of the boundary pattern portionscome into contact with each other. The number of contact points of theboundary pattern portions can be reduced, thus minimizing the contactareas of the boundary pattern portions so as to ensure a gapcommunicating with the boundary pattern portion. Accordingly, when theheat transfer member serves as a condenser, smooth flow of the heatexchange fluid in liquid phase can be ensured without causing buildup,thus enhancing the heat exchange effectiveness in the heat transferface. The recesses or projections of the smooth wave-shaped crosssection improve formability of the boundary pattern portions, thusavoiding defects of the products.

[0021] In order to attain the aforementioned object, a method of thefifth aspect of the present invention for manufacturing a heat transfermember, comprises the step of:

[0022] subjecting a material to be worked, which is made of a metallicthin sheet, to a press forming utilizing a press-forming device, whilefeeding said material to be worked in a single feeding direction, toform a heat transfer member for a heat exchanger, said heat transfermember having a prescribed shape, said heat transfer member having on atleast one portion thereof a heat transfer face that has oppositesurfaces, which are to be come into contact with heat exchange fluids,respectively,

[0023] wherein:

[0024] said press-forming device comprises a main mold for forming theheat transfer face, said main mold having prescribed patterns ofirregularity, which are placed in prescribed front and rear zones in thefeeding direction of the material to be worked so as to be symmetricalto each other with respect to a central position between said front andrear zones and be in an equal positional relationship relative to saidcentral position in a perpendicular direction to said feeding directionof said material to be worked;

[0025] said material to be worked is press-formed by means of said mainmold of said press-forming device so that at least one set ofpress-formed portions are placed without forming a gap therebetween,thereby forming the heat transfer member.

[0026] According to the fifth aspect of the present invention, thematerial to be worked is press-formed by means of the press-formingdevice, which comprises the main mold having the prescribed patterns ofirregularity, which are placed in the front and rear zones in thefeeding direction of the material to be worked so as to be symmetricalto each other so that a single press-forming operation of thepress-forming device provides the press-formed portions in theabove-mentioned front and rear zones, which have the patterns ofirregularity in an equal positional relationship relative to the centralposition in the perpendicular direction to the feeding direction of thematerial to be worked. Accordingly, it is possible to provide asubstantially uniform forming condition in the prescribed regions of thepress-formed portions, which are adjacent to the non-pressed portions ofthe material to be worked, irrespective of a shape of the intermediateportion of the main mold in the feeding direction. Degree of drawing ofthe material to be worked from the non-pressed portion into thepress-formed portion in the press formation therefore becomessubstantially uniform in the boundary position between the press-formedportion and the non-pressed portion. The residual distortion can beprevented from occurring on the press-formed portion and the non-pressedportion, after completion of the press formation, thus avoiding abnormaldeformation of the heat transfer member finally obtained.

[0027] In the sixth aspect of the present invention, the patterns ofirregularity of the main mold of said press-forming device, which areplaced in the front and rear zones in the feeding direction of thematerial to be worked, may be identical to each other; and of thepress-formed portions of the material to be worked, which have beenformed utilizing said press-forming device, the press-formed portionhaving the pattern of irregularity, which is placed on a side of therear zone in said feeding direction, may be subjected to a re-pressingstep utilizing the pattern of irregularity, which is placed on a side ofthe front zone in said feeding direction in said main mold, whileintermittently feeding said material to be worked by a prescribedlength, thereby forming the sets of press-formed portions on thematerial to be worked.

[0028] According to the sixth aspect of the present invention, thepatterns of irregularity of the main mold of the press-forming device,which are placed in the front and rear zones in the feeding direction ofthe material to be worked, are identical to each other. Of thepress-formed portions of the material to be worked, which have beenformed utilizing the press-forming device, the press-formed portionhaving the pattern of irregularity, which is placed on the side of therear zone in the feeding direction, is subjected to the re-pressing steputilizing the pattern of irregularity, which is placed on the side ofthe front zone in the feeding direction in the main mold. As a result, adual-pressing operation is carried out in the front and rear zones inthe feeding direction of the material to be worked so as to hold a partof the press-formed portion through the re-pressing step, thuscontrolling movement of material from the press-formed portion into theportion to be newly press-formed. It is therefore possible to preventoccurrence of distortion due to the press-forming step, thus reducingresidual distortion in the press-formed portion and the non-pressedportion, after completion of the press formation and avoiding abnormaldeformation of the heat transfer member finally obtained. In addition,the dual-pressing operation, applied to the press-formed portion of theheat transfer member, based on the patterns of irregularity maximizesthe effective operative portions serving as the heat transfer face,while preventing deformation of the press-formed portion.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029]FIG. 1 is a front view illustrating a heat transfer member inaccordance with the embodiment of the present invention;

[0030]FIG. 2 is a descriptive view illustrating a state in which thepress-forming step is being carried out in accordance with theembodiment of the present invention;

[0031]FIG. 3 is a descriptive view of a press-forming operation, whichis applied to one end of the material to be worked in accordance withthe embodiment of the method of the present invention for manufacturingthe heat transfer member;

[0032]FIG. 4 is a descriptive view of a press-forming operation, whichis applied to the intermediate portion of the material to be worked inaccordance with the embodiment of the method of the present inventionfor manufacturing the heat transfer member;

[0033]FIG. 5 is a descriptive view of a press-forming operation, whichis applied to the other end of the material to be worked in accordancewith the embodiment of the method of the present invention formanufacturing the heat transfer member;

[0034]FIG. 6 is a partial enlarged view of the heat transfer member ofthe embodiment of the present invention;

[0035]FIG. 7 is an enlarged perspective view of a portion “A” as shownin FIG. 6;

[0036]FIG. 8 is a vertical cross-sectional view of an essentialcomponent of the central pattern portion of the heat transfer member ofthe embodiment of the present invention;

[0037]FIG. 9(A) is an enlarged vertical cross-sectional view of theessential component of the central pattern portion of the heat transfermember of the embodiment of the present invention and FIG. 9(B) is anenlarged horizontal cross-sectional view thereof; and

[0038]FIG. 10 is a front view of the heat transfer member of the otherembodiment of the present invention..

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] Now, the embodiment of the present invention will be described indetail below with reference to FIGS. 1 to 9. FIG. 1 is a front viewillustrating a heat transfer member in accordance with the embodiment ofthe present invention; FIG. 2 is a descriptive view illustrating a statein which the press-forming step is being carried out in accordance withthe embodiment of the present invention; FIG. 3 is a descriptive view ofa press-forming operation, which is applied to one end of the materialto be worked in accordance with the embodiment of the method of thepresent invention for manufacturing the heat transfer member; FIG. 4 isa descriptive view of a press-forming operation, which is applied to theintermediate portion of the material to be worked in accordance with theembodiment of the method of the present invention for manufacturing theheat transfer member; FIG. 5 is a descriptive view of a press-formingoperation, which is applied to the other end of the material to beworked in accordance with the embodiment of the method of the presentinvention for manufacturing the heat transfer member; FIG. 6 is apartial enlarged view of the heat transfer member of the embodiment ofthe present invention; FIG. 7 is an enlarged perspective view of aportion “A” as shown in FIG. 6; FIG. 8 is a vertical cross-sectionalview of an essential component of the central pattern portion of theheat transfer member of the embodiment of the present invention; andFIG. 9(A) is an enlarged vertical cross-sectional view of the essentialcomponent of the central pattern portion of the heat transfer member ofthe embodiment of the present invention and FIG. 9(B) is an enlargedhorizontal cross-sectional view thereof.

[0040] The heat transfer member 100 as shown in FIGS. 1 to 9 inaccordance with the embodiment of the present invention has a structurein which press-formed portions are arranged, by feeding material to beworked 50, which is made of a rectangular metallic thin sheet, to aprescribed press-forming device 1 in the single feeding direction,forming a heat transfer face 110 on the central portion of the materialto be worked 50 by means of the press-forming device 1 and formingflange portions 120 in the periphery of the heat transfer face 110.

[0041] The heat transfer face 110 is a region having a prescribedirregularity, which is optimized to make heat transfer through contactof one surface of the heat transfer face 110 with a high temperaturefluid and contact of the other surface thereof with a low temperaturefluid. Such a heat transfer face 110 can be obtained by carrying out aplurality of press-forming steps utilizing the press-forming device 1.The heat transfer face 110 has unit regions of a central pattern portion111, a pair of heat exchanging irregularity pattern portions 112 andboundary pattern portions 113. The central pattern portion 111 has aplurality of projections provided with a prescribed pitch. The heatexchanging irregularity pattern portions 112 are provided on theopposite sides of the central pattern portion so as to symmetrical withrespect to the central pattern portion 111. The boundary patternportions 113 are provided on the respective outer sides of the heatexchanging irregularity pattern portions so as to be adjacent to therespective outer sides thereof. The boundary pattern portion 113 has aplurality of projections provided with the same pitch as the projectionsof the central pattern portion 111 so as to be in parallel with them.

[0042] The above-mentioned heat exchanging irregularity pattern portion112 is formed on the basis of the known pattern of irregularity, whichis provided with a wave-formed cross section having an excellent heattransfer property and with grooves through which condensed water can bedischarged rapidly. Description of the irregularity is omitted.

[0043] The boundary pattern portion 113 has the same width as thecentral pattern portion 111. Each of the central pattern portion 111 andthe boundary pattern portion 113 has a plurality of recesses orprojections, provide a smooth sine curve shaped cross section in adirection perpendicular to the direction of the recesses or projections.The recesses or projections of the smooth sine curve shaped crosssection improve formability of the central pattern portion 111 and theboundary pattern portions 113, thus avoiding defects of the products.

[0044] The flange portion 120 is composed of flat portions 121 having aprescribed width, which are disposed continuously along two sides of theperiphery of a rectangular shape, which are in parallel with the feedingdirection, and upward projections 122 continuously extending from theheat transfer face 110 along the other two sides, which areperpendicular to the feeding direction.

[0045] The press-forming device 1 for forming the above-described heattransfer member 100 includes a pair of upper and lower main molds 10 forforming the heat transfer face 110 and two pairs of auxiliary molds 20,30. The main molds 10 form the heat transfer face 110, which has theopposite surfaces to be brought into contact with heat exchange fluids,respectively. The auxiliary molds 20, 30 are disposed on upstream anddownstream sides of the main molds 10 in the feeding direction of thematerial, so as to be exchangeable. Detection devices (not shown) forjudging whether or not a prescribed portion to be press-formed of thematerial to be worked 50 reaches the respective press-forming positionare provided in the vicinity of each of the main molds 10 and theauxiliary molds 20, 30.

[0046] The main molds 10 have molding faces, which can form the centralpattern portion 111, the heat exchanging irregularity pattern portions112 and the boundary pattern portions 113 of the heat transfer face 110,in addition to the flat portion 121 of the flange portion 120.Especially, the main molds 10 form the pattern of irregularity on thematerial to be worked in places corresponding to the boundary patternportions 113 of the heat transfer face 110 at the front and rear zonesin the feeding direction, respectively. The patterns of irregularityformed in these places on the material to be worked are identical witheach other in shape.

[0047] Now, description will be given below of press-forming operationin the method of the embodiment of the present invention formanufacturing the heat transfer member. Such an operation is carried outon the assumption that a defect detection step is carried out previouslyso that only the material to be worked 50 having no defects is conveyedto the side of the press forming device 1.

[0048] The main molds 10 and the auxiliary molds 20, 30 of thepress-forming device 1 are previously kept in their initial state inwhich the respective upper and lower molds are separated from eachother. The material to be worked 50 is conveyed by means of a prescribedmaterial feeding unit (not shown) so that the one end of the material tobe worked 50 is inserted between the respective upper and lower molds.When the one end of the material to be worked 50 reach a position inwhich the press-forming step is to be carried out in the press-formingdevice 1, the feeding operation of the material to be worked 50 istemporarily stopped. The one end of the material to be worked 50 ispress-formed by means of the main molds 10 and the auxiliary mold 20 ofthe press-forming device 1 so that the uniform pressure is applied tothe material to be worked 50 to form press-formed portions having aprescribed irregularity in accordance with the respective molds in areliable manner (see FIG. 3).

[0049] The press-formed portion formed by means of the main molds 10includes the central pattern portion 111, the heat exchangingirregularity pattern portions 112 provided on the opposite sides of thecentral pattern portion 111 and the boundary pattern portions 113provided on the respective outer sides of the pair of heat exchangingirregularity pattern portions 112 (see FIG. 2). The boundary patternportions 113 formed substantially uniformly are placed in the vicinityof the non-pressed portion of the material to be worked 50. Accordingly,degree of drawing of material from the non-pressed portion into thepressed portion in the press formation becomes appropriately constant ina boundary between the press-formed portion and the non-pressed portion,thus reducing residual distortion in the press-formed portion and thenon-pressed portion after completion of the press formation.

[0050] After completion of the press-forming step applied to the one endof the material to be worked 50, the press-forming device 1 operates toseparate all the pairs of upper and lower molds from each other. Thefeeding operation of the material to be worked 50 is carried out againby means of the material feeding unit so that the material to be worked50 is subjected to the press-forming step utilizing only the main molds10. Here, a region of the material to be worked 50, which is to bepress-formed newly, includes the boundary pattern portion 113 of theportions as being already press-formed, which boundary pattern portion113 has been formed in the rear zone in the feeding direction. As aresult, such a boundary pattern portion 113 is then press-formed bymeans of the molds, which are placed in the front zone in the feedingdirection.

[0051] When the region of the material to be worked 50, which is to bepress-formed newly, reaches the press-forming position in thepress-forming device 1, the feeding operation of the material to beworked 50 is temporarily stopped. The adjacent portion of the materialto be worked 50, to the one end thereof is press-formed by means of themain molds 10 of the press-forming device 1 so that the uniform pressureis applied to the material to be worked 50 to form press-formed portionshaving a prescribed irregularity in accordance with the respective moldsin a reliable manner (see FIG. 4).

[0052] Then, the press-forming device 1 causes the respective molds toseparate from each other and the feeding operation of the material to beworked 50 is then carried out utilizing the material feeding unit sothat the region to be press-formed of the material to be worked 50reaches the press-forming position. The press-forming device 1 operatesto move the upper and lower molds closely to each other so that theregion of the material to be worked 50, which is to be press-formednewly, is press-formed. Then, a series of steps for transferring thematerial to be worked 50 and applying the press forming is repeated by atime of numbers of the regions of the material to be worked 50, whichare to be press-formed. Accordingly, a plurality of press-forming stepsare applied to the material to be worked 50, which is conveyed by aprescribed length for each of the press-forming steps, utilizing themain molds 10 of the press-forming device 1.

[0053] During such a plurality of press-forming steps utilizing the mainmolds 10, there is repeated the press-forming step, which is applied tothe boundary pattern portion 113, which has been press-formed in therear zone in the feeding direction, utilizing the molds placed in thefront zone in the press-forming device 1 in the feeding direction.Accordingly, there is provided a condition in which the press-formedportions are arranged on the material to be worked 50 in the feedingdirection of the material to be worked 50 and the single boundarypattern portion 113 is placed in the vicinity of the heat exchangingirregularity pattern portion 112.

[0054] After completion of the prescribed number of press-forming stepsutilizing the main molds 10, the material to be worked 50 is subjectedto the last press-forming steps utilizing the auxiliary molds 30 and themain molds 10, which are placed in the rear zone in the feedingdirection of the material to be worked 50. The main molds 10 and theauxiliary molds 30 are kept in their initial state in which therespective upper and lower molds are separated from each other. Then,the material feeding unit conveys the material to be worked 50. When theother end of the material to be worked 50 moves to the press formingposition, the feeding operation of the material to be worked 50 istemporarily stopped. The main molds 10 and the auxiliary molds 30 pressthe other end of the material to be worked 50 so that the uniformpressure is applied to the material to be worked 50 to form press-formedportions having a prescribed irregularity in accordance with therespective molds in a reliable manner. Also in these last press-formingsteps, the boundary pattern portion 113 of the portions as being alreadypress-formed, which boundary pattern portion 113 has been formed in therear zone in the feeding direction, is then press-formed by means of themolds, which are placed in the front zone in the feeding direction.

[0055] After completion of the press-forming step utilizing the mainmolds 10 and the auxiliary molds 30, the press-forming device 1 operatesto separate all the molds from each other. The feeding operation of thematerial to be worked 50 is carried out again by means of the materialfeeding unit. The material to be worked 50 is conveyed in the feedingdirection and then discharged from the upper and lower molds of thepress-forming device 1. The material to be worked 50 thus press-formedis then conveyed to a place in which the next steps are to be carriedout.

[0056] Now, description will be given below of the heat transfer memberas manufactured of the embodiment of the present invention. Thepress-forming steps are applied to the metallic sheet serving as thematerial to be worked, utilizing the press-forming device 1. The heattransfer member 100, which has been discharged from the press-formingdevice 1, is placed on the other transfer member 100 as manufactured inthe same manner so that the inner surfaces of them face each other andthe latter is positioned upside down. These heat transfer members 100are welded together at the flat portions of the flange portion 120 intoa united body serving as a set of heat exchanger unit 200. An essentialcomponent of a heat exchanger is composed of a plural set of heatexchanger units 200 thus obtained.

[0057] When the heat transfer member 100 is placed on the other transfermember 100 so that the inner surfaces of them face each other and thelatter is positioned upside down, the flat portions 121 of these twoheat transfer members 100 come into close contact with each other andthe central pattern portions 111 and the boundary pattern portions 113of these two heat transfer members 100 come into contact with each otherso that the prescribed gap is formed between the two heat transfermembers 100 (see FIG. 8). As a result, there are formed an internalcavity, which is surrounded by the flange portions 120 and therespective heat transfer faces 110, as well as a passage 130 formed bythe projections 122, which communicates with the internal cavity (seeFIG. 7). The position of the passage 130 can easily be set bydetermination of the position of the projection 122.

[0058] The projections of the irregularities of the central patternportions 111 and the boundary pattern portions 113, which come intocontact with each other, form the gaps in a place corresponding to therecesses thereof so that heat exchange fluid can flow through these gaps(see FIG. 9). The contact areas between the central pattern portions 111and the boundary pattern portions 113 can be minimized so that heatexchange fluids can flow smoothly along the opposite surfaces of theheat transfer face of the heat transfer member 100, thus enhancing theheat exchange effectiveness.

[0059] The two heat transfer members 100 are assembled into the heatexchanger unit 200 so that heat exchange fluid can flow in and out ofthe internal cavity through the passage 130 formed by the projections122. Flowing fluid to be heat-exchanged on the outer surface of the heattransfer member 200 provides a heat exchange operation. When the heatexchange fluid in gaseous phase flows in the internal cavity of the heatexchanger unit 200 and the other heat exchange fluid having asufficiently low temperature flows outside the heat exchanger unit 200,the heat exchange fluid in gaseous phase in the internal cavity iscooled to be condensed. As a result, condensed water flow down along theheat transfer face 110, thus effectively utilizing the heat transferunit 200 as the condenser. In such a case, the condensed water iscollected from the heat exchanging irregularity pattern portions 112 ofthe heat transfer face 110 into the central pattern portion 111 and theboundary pattern portion 113 so as to fall down rapidly through the gapsin the irregularities of the central pattern portion 111 and theboundary pattern portion 113, thus discharging the condensed water in anappropriate manner without causing buildup and ensuring the sufficientheat exchange effectiveness.

[0060] When a plurality of sets of the heat exchanger units 200, each ofwhich is formed into the united body, are placed one upon another toconstitute an essential component of a heat exchanger, the projectionsof the central pattern portion 111 and the boundary pattern portion 113,and the projections 122 of the flange portion 120 of the heat transferface 110 come into contact with the corresponding projections of theother heat transfer face 110, thus maintaining the appropriate gapbetween the two heat transfer faces 110.

[0061] According to the heat transfer member of the embodiment of thepresent invention, there are formed the central pattern portion 111having the projections, the heat exchanging irregularity patternportions 112 provided on the opposite sides of the central patternportion 111 so as to be symmetrical with respect to the central patternportion 111, and the boundary pattern portions 113 having theprojections in the same manner as the central pattern portion 111 sothat these portions form the single heat transfer face 110. When theheat transfer member 100 is placed on the other heat transfer member 100so that the inner surfaces of them face each other and the latter ispositioned upside down, the projections of the central pattern portion111 and the projections of the boundary pattern portion 113 of the oneheat transfer member come into close contact with those of the otherheat transfer member, respectively. It is therefore possible to maintaina constant distance between the heat transfer members 100, thusproviding a uniform heat exchanging property, even when there is a largedifference in pressure between the heat transfer fluids, which flow onthe opposite surfaces of the heat transfer face 110.

[0062] According to the method of the present invention formanufacturing the heat transfer member, during a plurality ofpress-forming steps applied to the material to be worked 50 utilizingthe press-forming device 1, the boundary pattern portion 113 of theportions as being already press-formed, which boundary pattern portion113 has been formed in the rear zone in the feeding direction, ispress-formed again by means of the molds, which are placed in the frontzone in the feeding direction. Accordingly, the boundary pattern portion113 as press-formed is held to minimize drawing of material from theportion as press-formed into the portion to be press-formed newly, thusreducing occurrence of distortion in the press-formed portion due to thenew press formation and reducing residual distortion in the press-formedportion and the non-pressed portion after completion of the pressformation. Abnormal deformation of the heat transfer member 100 asfinally obtained can therefore be prevented.

[0063] In the above-described embodiment of the heat transfer member ofthe present invention, a plurality of sets of the press-formed portionsformed by means of the press-forming device 1 in the prescribedarrangement forms the single heat transfer face 110. The presentinvention is not limited only to such an embodiment. There may beprovided a single set of press-formed portions, which includes thecentral pattern portion 111, the heat exchanging irregularity patternportions 112 provided on the opposite sides of the central patternportion 111 and the boundary pattern portions 113 provided on therespective outer sides of the pair of heat exchanging irregularitypattern portions 112. Such a structure makes it possible to provide asmaller-sized heat transfer member 100, coping with a compact heatexchanger.

[0064] In the above-described embodiment of the heat transfer member ofthe present invention, the press-formed portions are formed in theprescribed arrangement by means of the press-forming device 1 so thatthe patterns are arranged in the horizontal direction. The presentinvention is not limited only to such an embodiment. The molding facesof the press-forming device 1 may be changed so that the central patternportion 111 and the heat exchanging irregularity pattern portions 112are formed on the material to be worked 50 in a parallel direction tothe feeding direction of the material to be worked 50 and that thepatterns of irregularity having the same shape are formed incorrespondence to the above-mentioned boundary pattern portions 113, inthe front and rear zones in the feeding direction, in an equalpositional relationship relative to the central position in aperpendicular direction to the feeding direction of the material to beworked. In such a case, there is provided the heat transfer face 110 inwhich the boundary pattern portion 113 is held between the upper set ofcentral pattern portion 111 and the heat exchanging irregularity patternportion 112 and the lower set of central pattern portion 111 and theheat exchanging irregularity pattern portion 112 as shown in FIG. 10.When the heat transfer member 100 is placed on the other heat transfermember 100 so that the inner surfaces of them face each other and thelatter is positioned upside down, the projections of the central patternportion 111 and the projections of the boundary pattern portion 113 ofthe one heat transfer member come into close contact with those of theother heat transfer member, respectively. It is therefore possible tomaintain a constant distance between the heat transfer member 100. Evenwhen the respective ends of the central pattern portion 111 and the heatexchanging irregularity pattern portion 112 has a non-uniform pattern inthe horizontal direction of the heat transfer face 110, the boundarypattern portions 113 formed substantially uniformly are placed in thevicinity of such a non-uniform pattern, the boundary pattern portion113, which is located between the central pattern portion 111 and theheat exchanging irregularity pattern portion 112 is subjected to thedual press forming so that the boundary pattern portion 113 is heldduring the second press forming to prevent drawing of material from theportion as press-formed into the portion to be press-formed newly. It istherefore possible to reducing residual distortion after completion ofthe press formation, thus preventing abnormal deformation of the heattransfer member 100.

[0065] In the above-described embodiment of the heat transfer member ofthe present invention, the boundary pattern portion 113 and the centralpattern portion 111 has the same width. The present invention is notlimited only to such an embodiment. The patterns of irregularity, whichare placed in the front and rear zones in the feeding direction of themolding face of the main molds of the press-forming device 1 so as tocorrespond to the boundary pattern portion 113 of the heat transfermember 100, may be reduced to half of the central pattern portion 111.In such a case, the feeding length of the material to be worked ischanged so that only a portion, which has not as yet been subjected tothe press forming, is press-formed newly, without applying the dualpress-forming. The width of the boundary pattern portion 113, which isplaced between the heat exchanging irregularity pattern portions 112becomes equal to the central pattern portion 111. The width of theboundary pattern portion 113, which is placed the outermost side of theheat transfer face 110, is half of the central pattern portion 111.

[0066] In the above-described embodiment of the heat transfer member ofthe present invention, the central pattern portion 111 and the boundarypattern portion 113 have a smooth sine wave-shaped cross section in adirection perpendicular to the recesses or projections. Each of the heatexchanging irregularity pattern portions 112 of the heat transfer face110 may have grooves or projections so as to form a wave-formed crosssection. Such a structure improves formability of the heat exchangingirregularity pattern portion 112, thus avoiding defects of the products.

[0067] According to the first aspect of the present invention, there isformed a single set or a plurality of sets of press-formed portioncomprising the central pattern portion having the plurality of recessesor projections, the pair of heat exchanging irregularity patternportions provided on the opposite sides of the central pattern portionso as to be symmetrical with respect to the central pattern portion andthe at least one boundary pattern portion having the plurality ofrecesses or projections, which is provided on the at least one of therespective outer sides of the pair of heat exchanging irregularitypattern portions, so that the whole of the central pattern portion, theheat exchanging irregularity pattern portions and the boundary patternportion serves as the single heat transfer face. When the heat transfermember is placed on the other heat transfer member so that the innersurfaces of them face each other and the latter is positioned upsidedown, the projections of the central pattern portion and the projectionsof the boundary pattern portion of the one heat transfer member comeinto close contact with those of the other heat transfer member,respectively. It is therefore possible to maintain a constant distancebetween the heat transfer members, thus coping with a case where thereis a large difference in pressure between the heat transfer fluids.Accordingly, a uniform heat exchange property can be provided and areliable strength of the whole heat exchanger, which is composed of thecombined heat transfer members, can be obtained. Even when the heatexchanging irregularity pattern portion has a non-uniform pattern in thevertical direction of the heat transfer face, the boundary patternportions having the uniform pattern, are disposed outside the heatexchanging irregularity pattern portion, so as to reduce residualdistortion after completion of the press formation, preventing abnormaldeformation of the respective portions of the heat transfer member.

[0068] According to the second aspect of the present invention, there isformed a single set of a plurality of sets of press-formed portioncomprising the central pattern portion having the plurality of recessesor projections, the pair of heat exchanging irregularity patternportions provided on the opposite sides of the central pattern portionso as to be symmetrical with respect to the central pattern portion andthe at least one boundary pattern portion having the plurality ofrecesses or projections, which is provided on the at least one of thepair of opposite connection sides. The at least one boundary patternportion has the prescribed width and the plurality of recesses orprojections with a prescribed pitch so as to be perpendicular to therecesses or projections of the central pattern portion. When the heattransfer member is placed on the other heat transfer member so that theinner surfaces of them face each other and the latter is positionedupside down, the projections of the central pattern portion and theprojections of the boundary pattern portion of the one heat transfermember come into close contact with those of the other heat transfermember, respectively. It is therefore possible to maintain a constantdistance between the heat transfer members, thus coping with a casewhere there is large difference between the heat transfer fluids.Accordingly, a uniform heat exchange property can be provided and areliable strength of the whole heat exchanger, which is composed of thecombined heat transfer members, can be obtained. Even when the centralpattern portion and the heat exchanging irregularity pattern portionhave a non-uniform pattern in the horizontal direction of the heattransfer face, the boundary pattern portions having the uniform pattern,are disposed on the adjacent portions, so as to reduce residualdistortion after completion of the press formation, preventing abnormaldeformation of the respective portions of the heat transfer member.

[0069] According to the third aspect of the present invention, therecesses or projections of the boundary pattern portion provide thesmooth wave-shaped cross section in the direction perpendicular to thedirection of the recesses or projections thereof. When the heat transfermember is placed on the other heat transfer member so that the innersurfaces of them face each other and the latter is positioned upsidedown, the respective projections of the boundary pattern portions comeinto contact with each other. The number of contact points of theboundary pattern portions can be reduced, thus minimizing the contactareas of the boundary pattern portions so as to ensure a gapcommunicating with the boundary pattern portion. Accordingly, when theheat transfer member serves as a condenser, smooth flow of the heatexchange fluid in liquid phase can be ensured without causing buildup,thus enhancing the heat exchange effectiveness in the heat transferface. The recesses or projections of the smooth wave-shaped crosssection improve formability of the boundary pattern portions, thusavoiding defects of the products.

[0070] According to the fourth aspect of the present invention, therecesses or projections of the boundary pattern portion provide thesmooth wave-shaped cross section in the direction perpendicular to thedirection of the recesses or projections thereof. When the heat transfermember is placed on the other heat transfer member so that the innersurfaces of them face each other and the latter is positioned upsidedown, the respective projections of the boundary pattern portions comeinto contact with each other. The number of contact points of theboundary pattern portions can be reduced, thus minimizing the contactareas of the boundary pattern portions so as to ensure a gapcommunicating with the boundary pattern portion. Accordingly, when theheat transfer member serves as a condenser, smooth flow of the heatexchange fluid in liquid phase can be ensured without causing buildup,thus enhancing the heat exchange effectiveness in the heat transferface. The recesses or projections of the smooth wave-shaped crosssection improve formability of the boundary pattern portions, thusavoiding defects of the products.

[0071] According to the fifth aspect of the present invention, thematerial to be worked is press-formed by means of the press-formingdevice, which comprises the main mold having the prescribed patterns ofirregularity, which are placed in the front and rear zones in thefeeding direction of the material to be worked so as to be symmetricalto each other so that a single press-forming operation of thepress-forming device provides the press-formed portions in theabove-mentioned front and rear zones, which have the patterns ofirregularity in an equal positional relationship relative to the centralposition in the perpendicular direction to the feeding direction of thematerial to be worked. Accordingly, it is possible to provide asubstantially uniform forming condition in the prescribed regions of thepress-formed portions, which are adjacent to the non-pressed portions ofthe material to be worked, irrespective of a shape of the intermediateportion of the main mold in the feeding direction. Degree of drawing ofthe material to be worked from the non-pressed portion into thepress-formed portion in the press formation therefore becomessubstantially uniform in the boundary position between the press-formedportion and the non-pressed portion. The residual distortion can beprevented from occurring on the press-formed portion and the non-pressedportion, after completion of the press formation, thus avoiding abnormaldeformation of the heat transfer member finally obtained.

[0072] According to the sixth aspect of the present invention, thepatterns of irregularity of the main mold of the press-forming device,which are placed in the front and rear zones in the feeding direction ofthe material to be worked, are identical to each other. Of thepress-formed portions of the material to be worked, which have beenformed utilizing the press-forming device, the press-formed portionhaving the pattern of irregularity, which is placed on the side of therear zone in the feeding direction, is subjected to the re-pressing steputilizing the pattern of irregularity, which is placed on the side ofthe front zone in the feeding direction in the main mold. As a result, adual-pressing operation is carried out in the front and rear zones inthe feeding direction of the material to be worked so as to hold a partof the press-formed portion through the re-pressing step, thuscontrolling movement of material from the press-formed portion into theportion to be newly press-formed. It is therefore possible to preventoccurrence of distortion due to the press-forming step, thus reducingresidual distortion in the press-formed portion and the non-pressedportion, after completion of the press formation and avoiding abnormaldeformation of the heat transfer member finally obtained. In addition,the dual-pressing operation, applied to the press-formed portion of theheat transfer member, based on the patterns of irregularity maximizesthe effective operative portions serving as the heat transfer face,while preventing deformation of the press-formed portion.

What is claimed is:
 1. A heat transfer member for a heat exchanger,which is press-formed of a metallic thin sheet material into aprescribed shape by means of molds of a press forming device so thatsaid heat transfer member has on at least one portion thereof a heattransfer face having opposite surfaces, which are to be brought intocontact with heat exchange fluids, respectively, wherein: said heattransfer face comprises at least one set of irregularity patternsarranged in a row, each of said at least one set of irregularity patternunits comprising (i) a central pattern portion having a plurality ofrecesses or projections provided with a prescribed pitch, (ii) a pair ofheat exchanging irregularity pattern portions provided on opposite sidesof said central pattern portion so as to be symmetrical with respect tosaid central pattern portion and (iii) at least one boundary patternportion provided on at least one of respective outer sides of said pairof heat exchanging irregularity pattern portions so as to be adjacent tothe respective outer sides thereof, said at least one boundary patternportions having a prescribed width and a plurality of recesses orprojections provided with a same pitch as said plurality of recesses orprojections of said central pattern portion so as to be in paralleltherewith.
 2. A heat transfer member for a heat exchanger, which ispress-formed of a metallic thin sheet material into a prescribed shapeby means of molds of a press forming device so that said heat transfermember has on at least one portion thereof a heat transfer face havingopposite surfaces, which are to be brought into contact with heatexchange fluids, respectively, wherein: said heat transfer facecomprises at least one set of irregularity patterns arranged in a row,each of said at least one set of irregularity pattern units comprising(i) a central pattern portion having a plurality of recesses orprojections provided with a prescribed pitch, said central portionhaving two pairs of opposite sides, (ii) a pair of heat exchangingirregularity pattern portions provided on one of said two pairs ofopposite sides of said central pattern portion so as to be symmetricalwith respect to said central pattern portion, said pair of heatexchanging irregularity pattern portions and said central patternforming a pair of opposite connection sides extending along an other ofsaid two pairs of opposite sides of said central pattern portion, and(iii) at least one boundary pattern portion provided on at least one ofsaid pair of opposite connection sides, said at least one boundarypattern portion having a prescribed width and a plurality of recesses orprojections with a prescribed pitch so as to be perpendicular to saidplurality of recesses or projections of said central pattern portion. 3.The heat transfer member as claimed in claim 2, wherein: said boundarypattern portion continues in a form of grooves or projections in adirection perpendicular to a direction of said plurality of recesses orprojections thereof so as to form a plurality of rows of irregularities,providing a smooth wave-shaped cross section.
 4. The heat transfermember as claimed in claim 1 or 2, wherein: said central pattern portionor said boundary pattern portion continues in a form of grooves orprojections in a direction of said plurality of recesses or projectionsthereof so as to form a plurality of rows of irregularities, providing asmooth wave-shaped cross section.
 5. A method for manufacturing a heattransfer member, comprising the step of: subjecting a material to beworked, which is made of a metallic thin sheet, to a press formingutilizing a press-forming device, while feeding said material to beworked in a single feeding direction, to form a heat transfer member fora heat exchanger, said heat transfer member having a prescribed shape,said heat transfer member having on at least one portion thereof a heattransfer face that has opposite surfaces, which are to be come intocontact with heat exchange fluids, respectively, wherein: saidpress-forming device comprises a main mold for forming the heat transferface, said main mold having prescribed patterns of irregularity, whichare placed in prescribed front and rear zones in the feeding directionof the material to be worked so as to be symmetrical to each other withrespect to a central position between said front and rear zones and bein an equal positional relationship relative to said central position ina perpendicular direction to said feeding direction of said material tobe worked; said material to be worked is press-formed by means of saidmain mold of said press-forming device so that at least one set ofpress-formed portions are placed without forming a gap therebetween,thereby forming the heat transfer member.
 6. The method as claimed inclaim 5, wherein: the patterns of irregularity of the main mold of saidpress-forming device, which are placed in the front and rear zones inthe feeding direction of the material to be worked, are identical toeach other; and of the press-formed portions of the material to beworked, which have been formed utilizing said press-forming device, thepress-formed portion having the pattern of irregularity, which is placedon a side of the rear zone in said feeding direction, is subjected to are-pressing step utilizing the pattern of irregularity, which is placedon a side of the front zone in said feeding direction in said main mold,while intermittently feeding said material to be worked by a prescribedlength, thereby forming the sets of press-formed portions on thematerial to be worked.